package com.muqi.app.viewpager.tabtitle;

import com.easemob.easeui.R;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class CategoryTabStrip extends HorizontalScrollView {
	private LayoutInflater mLayoutInflater;
	private final PageListener pageListener = new PageListener();
	private ViewPager pager;
	private LinearLayout tabsContainer;
	private int tabCount;
	
	private int currentPosition = 0;
	private float currentPositionOffset = 0f;
	
	private Rect indicatorRect;
	
	private LinearLayout.LayoutParams defaultTabLayoutParams;
	
	private int scrollOffset = 10;
	private int lastScrollX = 0;
	
	private Drawable indicator;
	private TextDrawable[] drawables;
	private Drawable left_edge;
    private Drawable right_edge;
	
	public CategoryTabStrip(Context context) {
		this(context, null);
	}

	public CategoryTabStrip(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	@SuppressWarnings("deprecation")
	public CategoryTabStrip(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);

		mLayoutInflater = LayoutInflater.from(context);
		drawables = new TextDrawable[3];
		int i = 0;
		while (i < drawables.length) {
			drawables[i] = new TextDrawable(getContext());
            i++;
        }
		
		indicatorRect = new Rect();
		
		setFillViewport(true);
		setWillNotDraw(false);

		tabsContainer = new LinearLayout(context);
		tabsContainer.setOrientation(LinearLayout.HORIZONTAL);
		tabsContainer.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
		addView(tabsContainer);
		
		DisplayMetrics dm = getResources().getDisplayMetrics();
		scrollOffset = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, scrollOffset, dm);
		
		defaultTabLayoutParams = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);

		indicator = getResources().getDrawable(R.drawable.bg_category_indicator);
		left_edge = getResources().getDrawable(R.drawable.ic_category_left_edge);
        right_edge = getResources().getDrawable(R.drawable.ic_category_right_edge);
	}

	@SuppressWarnings("deprecation")
	public void setViewPager(ViewPager pager) {
		this.pager = pager;

		if (pager.getAdapter() == null) {
			throw new IllegalStateException("ViewPager does not have adapter instance.");
		}

		pager.setOnPageChangeListener(pageListener);

		notifyDataSetChanged();
	}

	public void notifyDataSetChanged() {
		tabsContainer.removeAllViews();

		tabCount = pager.getAdapter().getCount();

		for (int i = 0; i < tabCount; i++) {
			addTab(i, pager.getAdapter().getPageTitle(i).toString());
		}

	}

	private void addTab(final int position, String title) {
		ViewGroup tab = (ViewGroup)mLayoutInflater.inflate(R.layout.category_tab, this, false);
		TextView category_text = (TextView) tab.findViewById(R.id.category_text);
		category_text.setText(title);
		category_text.setGravity(Gravity.CENTER);
		category_text.setSingleLine();
		category_text.setFocusable(true);
		category_text.setTextColor(getResources().getColor(R.color.category_tab_text));
		tab.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				pager.setCurrentItem(position);
			}
		});

		tabsContainer.addView(tab, position, defaultTabLayoutParams);
	}

	// ���㻬�������о��θ����������������λ��
	private void calculateIndicatorRect(Rect rect) {
		ViewGroup currentTab = (ViewGroup)tabsContainer.getChildAt(currentPosition);
		TextView category_text = (TextView) currentTab.findViewById(R.id.category_text);
		
		float left = (float) (currentTab.getLeft() + category_text.getLeft());
        float width = ((float) category_text.getWidth()) + left;
        
        if (currentPositionOffset > 0f && currentPosition < tabCount - 1) {
        	ViewGroup nextTab = (ViewGroup)tabsContainer.getChildAt(currentPosition + 1);
			TextView next_category_text = (TextView) nextTab.findViewById(R.id.category_text);
			
			float next_left = (float) (nextTab.getLeft() + next_category_text.getLeft());
			left = left * (1.0f - currentPositionOffset) + next_left * currentPositionOffset;
			width = width * (1.0f - currentPositionOffset) + currentPositionOffset * (((float) next_category_text.getWidth()) + next_left);
        }
        
        rect.set(((int) left) + getPaddingLeft(), getPaddingTop() + currentTab.getTop() + category_text.getTop(), 
				((int) width) + getPaddingLeft(), currentTab.getTop() + getPaddingTop() + category_text.getTop() + category_text.getHeight());

	}
	
	// ���������Χ
	private int getScrollRange() {
        return getChildCount() > 0 ? Math.max(0, getChildAt(0).getWidth() - getWidth() + getPaddingLeft() + getPaddingRight()) : 0;
    }
	
	private void scrollToChild(int position, int offset) {

		if (tabCount == 0) {
			return;
		}
		
        calculateIndicatorRect(indicatorRect);

		int newScrollX = lastScrollX;
		if (indicatorRect.left < getScrollX() + scrollOffset) {
            newScrollX = indicatorRect.left - scrollOffset;
        } else if (indicatorRect.right > getScrollX() + getWidth() - scrollOffset) {
            newScrollX = indicatorRect.right - getWidth() + scrollOffset;
        }
		if (newScrollX != lastScrollX) {
			lastScrollX = newScrollX;
			scrollTo(newScrollX, 0);
		}

	}

	@Override
	public void draw(Canvas canvas) {
		super.draw(canvas);
		
        calculateIndicatorRect(indicatorRect);
        
		if(indicator != null) {
			indicator.setBounds(indicatorRect);
			indicator.draw(canvas);
		}
		
        int i = 0;
        while (i < tabsContainer.getChildCount()) {
            if (i < currentPosition - 1 || i > currentPosition + 1) {
                i++;
            } else {
            	ViewGroup tab = (ViewGroup)tabsContainer.getChildAt(i);
            	TextView category_text = (TextView) tab.findViewById(R.id.category_text);
                if (category_text != null) {
                    TextDrawable textDrawable = drawables[i - currentPosition + 1];
                    int save = canvas.save();
                    calculateIndicatorRect(indicatorRect);
                    canvas.clipRect(indicatorRect);
                    textDrawable.setText(category_text.getText());
                    textDrawable.setTextSize(0, category_text.getTextSize());
                    textDrawable.setTextColor(getResources().getColor(R.color.category_tab_highlight_text));
                    int left = tab.getLeft() + category_text.getLeft() + (category_text.getWidth() - textDrawable.getIntrinsicWidth()) / 2 + getPaddingLeft();
                    int top = tab.getTop() + category_text.getTop() + (category_text.getHeight() - textDrawable.getIntrinsicHeight()) / 2 + getPaddingTop();
                    textDrawable.setBounds(left, top, textDrawable.getIntrinsicWidth() + left, textDrawable.getIntrinsicHeight() + top);
                    textDrawable.draw(canvas);
                    canvas.restoreToCount(save);
                }
                i++;
            }
        }
        
        i = canvas.save();
        int top = getScrollX();
        int height = getHeight();
        int width = getWidth();
        canvas.translate((float) top, 0.0f);
        if (left_edge == null || top <= 0) {
            if (right_edge == null || top >= getScrollRange()) {
                canvas.restoreToCount(i);
            }
            right_edge.setBounds(width - right_edge.getIntrinsicWidth(), 0, width, height);
            right_edge.draw(canvas);
            canvas.restoreToCount(i);
        }
        left_edge.setBounds(0, 0, left_edge.getIntrinsicWidth(), height);
        left_edge.draw(canvas);
        if (right_edge == null || top >= getScrollRange()) {
            canvas.restoreToCount(i);
        }
        right_edge.setBounds(width - right_edge.getIntrinsicWidth(), 0, width, height);
        right_edge.draw(canvas);
        canvas.restoreToCount(i);
	}

	private class PageListener implements OnPageChangeListener {

		@Override
		public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
			currentPosition = position;
			currentPositionOffset = positionOffset;
			
			scrollToChild(position, (int) (positionOffset * tabsContainer.getChildAt(position).getWidth()));

			invalidate();

		}

		@Override
		public void onPageScrollStateChanged(int state) {
			if (state == ViewPager.SCROLL_STATE_IDLE) {
				if(pager.getCurrentItem() == 0) {
					// �����������
					scrollTo(0, 0);
				} else if (pager.getCurrentItem() == tabCount - 1) {
					// ���������ұ�
					scrollTo(getScrollRange(), 0);
				} else {
					scrollToChild(pager.getCurrentItem(), 0);
				}
			}
		}

		@Override
		public void onPageSelected(int position) {

		}

	}

}
